Question

The valence electronic configuration of magnesium is

Short answer

Answer: The valence electronic configuration of magnesium is 3s^2.

Step-by-step solution

Find the atomic number of magnesium

The atomic number of magnesium is 12. The atomic number tells us the number of protons and electrons in a neutral atom. So magnesium has 12 electrons.

Distribute the electrons using the standard electron distribution method

Using the 2n^2 rule, we can figure out the distribution of electrons in different energy levels: - 1st shell: n=1, max electrons = 2(1)^2 = 2 - 2nd shell: n=2, max electrons = 2(2)^2 = 8 - 3rd shell: n=3, max electrons = 2(3)^2 = 18 We have 12 electrons to distribute: 1st shell: 2 electrons (all spaces filled) 2nd shell: 8 electrons (all spaces filled) 3rd shell: 2 electrons (still has room for more electrons)

Write the valence electronic configuration

The valence shell is the outermost shell, which is the 3rd shell in this case. Magnesium has 2 electrons in the 3rd shell. So, the valence electronic configuration of magnesium is 3s^2.

Key concepts

Atomic Number

The atomic number is a fundamental concept in chemistry and physics that refers to the number of protons found in the nucleus of an atom. It is represented by the letter 'Z' and is crucial because it uniquely identifies a chemical element. For neutral atoms, the atomic number also tells us the number of electrons orbiting the nucleus. This is because in a neutral atom, the number of protons (positively charged) equals the number of electrons (negatively charged) to maintain electrical neutrality.

For example, magnesium has an atomic number of 12. This means that any atom with 12 protons in its nucleus is an atom of magnesium. Correspondingly, it also has 12 electrons in a neutral state. Understanding the atomic number is essential for determining the electron configuration of an element, which further helps to predict an element's chemical properties and behavior.

Electron Distribution

Electron distribution, often visualized through the electron shell model, is the arrangement of electrons around an atom's nucleus. It follows specific rules, where electrons occupy energy levels or 'shells' starting from the closest to the nucleus and moving outwards. Each shell can hold a certain maximum number of electrons, typically given by the formula 2n², where 'n' is the shell number.

Let's distribute the electrons for magnesium, which has an atomic number of 12. The electron shells fill in the following order:

• 1st shell (n=1): can hold up to 2 electrons
• 2nd shell (n=2): can hold up to 8 electrons
• 3rd shell (n=3): can hold up to 18 electrons

Starting with the closest shell, we fill each shell to its maximum before moving to the next. For magnesium, the first shell is filled with 2 electrons, the second shell with 8, and the remaining 2 electrons go into the third shell. This distribution not only helps in understanding the electron configuration but also in determining an element's reactivity and the types of bonds it can form.

Valence Shell

The valence shell is the outermost shell of an atom that contains electrons. It plays a critical role in chemical bonding and reactions, as the electrons in this shell, known as valence electrons, are the ones that engage in chemical interactions with other atoms. The number of valence electrons determines many of the chemical properties of the element, including its valence or combining power. Elements with a full valence shell, such as the noble gases, are typically chemically inert, while those with partially filled valence shells tend to be more reactive.

In our case with magnesium, after distributing the electrons according to their shells, the third shell is the outermost and is thus the valence shell. It contains just 2 electrons. These 2 valence electrons determine magnesium's placement in Group 2 of the periodic table and its tendency to form stable compounds by losing these two electrons to achieve a filled second shell, which corresponds to the electron configuration of a noble gas (neon, in this case).

Electron Configuration

Electron configuration is the representation of the distribution of electrons in an atom's orbitals, or energy levels, and subshell. It provides a detailed account of where the electrons are likely to be found around the nucleus. This information is critical in understanding and predicting the atom's chemical behavior. The standard notation orders electrons from lowest to highest energy levels and further distinguishes subshells, which are s, p, d, and f.

The electron configuration for magnesium can be expressed as 1s²2s²2p⁶3s². This tells us that magnesium has two electrons in the first 's' orbital, two in the second 's' orbital, six in the second 'p' orbital, and two in the third 's' orbital. The last part, 3s², represents the valence electron configuration, indicating that magnesium's valence shell is the third shell and that it contains two electrons in the 's' subshell. The electron configuration is fundamental in predicting how an element might react, the types of bonds it will form, and its overall chemistry.